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The self-assessment return deadline is quickly approaching – if this is the first time for you that you are submitting a self-assessment tax return, do not fret. Our guide will provide you with everything you need to know in order to help you prepare for the self-assessment submission date, January 31st 2020.

What is a self-assessment tax return?

A self-assessment tax return is an annual report of earnings that sole traders and individuals send to HMRC at the same time each year. It is called a self-assessment because while you are filling out the return, you are also simultaneously responsible for calculating how much tax you have to pay.

Do I need to fill in a self-assessment tax return?

Ask yourself:

Do you work self employed, or are you a sole trader?

Are you responsible for your business’s tax payments?

Are you a business partner?

If you have answered “Yes” to any of the above questions, the likelihood is you will have to submit a Self-Assessment Tax Return.

To find out if you definitely need to fill in a tax return in more detail, you can follow this link here.

I am eligible to fill in a tax return – but how do I register?

Once you know for sure you need to submit a self-assessment return, you can register online following this link.

When you’ve registered, HMRC will send you a letter with your 10-digit Unique Taxpayer Reference. This process can take up to two weeks to arrive.

How do I fill in my tax return?

Filling in a return online

  • It is easiest to file your tax return online – you can do this once you have registered online with your Unique Taxpayer Reference.
  • You can complete your tax return through HMRC’s portal, or by using accounting software such as QuickBooks

Filling in a paper return

  • It is possible to fill out a paper return if you would prefer (known as an SA100), however this is often more complicated and paper returns are due to be submitted in October rather than January.
  • You can complete a paper tax return by following this link, where you can download a SA100 form which corresponds with the current tax year (2019 is for the 2018/2019 tax year)
  • Once you have completed the form, you can then send it via post to HMRC

If you are completing a paper tax return instead of filling it out online, this PDF which is available on is very useful

What is the deadline to file my tax return?

The current tax year started on 6 April 2019 and lasts until 5 April 2020. We are currently in tax year 2019/2020, and the deadline for self-assessment of the current tax year is 31st Jan 2021.

If you choose to do an online tax return for the tax year 2018/2019 (6 April 2018-5 April 2019):

You will have to submit the online tax return by 31st January 2020.

If you miss the deadline of submission, chances are you will have to pay a fine of £100, so try to avoid it.

What documents do I need to fill in my tax return?

It is handy to have the following documents at hand in order to help you fill out your tax return correctly:

  • P60
  • P11D
  • P45
  • P2
  • Your profit or loss account
  • Business records
  • Bank statements
  • Personal pension contribution certificates
Any other questions?

At J&P Accountants, we treat your business with the greatest care, in fact, as if it was our own business. We understand it can be stressful when you are submitting your self-assessment tax return for the first time, but we can help you. Read more about our the Self-Assessment services we offer here, or give us a call on 0161 637 1080 to speak to one of our advisors. Alternatively, you can write us an email to

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